Brunton J A, Bertolo R F, Pencharz P B, Ball R O
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta T6G 2P5, University of Toronto, Toronto, Ontario, Canada M5G 1X8.
Am J Physiol. 1999 Aug;277(2):E223-31. doi: 10.1152/ajpendo.1999.277.2.E223.
The indispensability of arginine has not been conclusively established in newborns. Because parenteral feeding bypasses the gut (where de novo synthesis of arginine occurs from proline), a dietary supply of arginine that is sufficient to maintain urea cycle function may be of greater importance during intravenous compared with enteral feeding. Two-day-old piglets (n = 12) were fed nutritionally complete diets for 5 days via either a central vein catheter (IV pigs, n = 6) or a gastric catheter (IG pigs, n = 6). Subsequently, each piglet received three incomplete test diets [arginine free (-ARG/+PRO), proline free (-PRO/+ARG), or arginine and proline free (-ARG/-PRO)] in a randomized crossover design. Plasma ammonia was assayed every 30 min for 8 h or until hyperammonemia was observed. Ammonia increased rapidly in IV pigs receiving -ARG/+PRO and -ARG/-PRO (84 +/- 36 and 74 +/- 37 micromol. l(-1). h(-1), respectively), requiring early diet cessation. A rapid increase was also exhibited by IG pigs receiving the -ARG/-PRO, but not the -ARG/+PRO diet (31 +/- 15 vs. 11 +/- 7 micromol. l(-1). h(-1), respectively, P < 0.05). Plasma arginine and proline were indicative of deficiency (IG and IV groups) when deplete diets were infused. Arginine is indispensable in parenteral and enteral nutrition, independent of dietary proline.
